e32b4172e4
The rain's column maths and fade colour move from MatrixRain into shell/rain.ts, and the request-once swarm name loader from useSwarmName into shell/swarm-name.ts. Both are plain functions with their input passed in, so tests cover them; the components keep the DOM and canvas work.
69 lines
2.3 KiB
JavaScript
69 lines
2.3 KiB
JavaScript
// The digital rain's arithmetic: columns, how they start and step, the glyph
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// drawn, and the fade colour. The random source is passed in, so each case is
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// exact. Run by `npm test`.
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import assert from "node:assert/strict";
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import { test } from "node:test";
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import {
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CELL,
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GLYPHS,
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columnsFor,
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fadeColorOf,
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glyphFor,
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startDrops,
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stepDrops,
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} from "../src/shell/rain.ts";
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const always = (n) => () => n;
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test("a canvas gets one column per cell, rounded up, and at least one", () => {
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assert.equal(columnsFor(CELL * 10), 10);
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assert.equal(columnsFor(CELL * 10 + 1), 11);
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assert.equal(columnsFor(0), 1);
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});
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test("columns start above the top, spread over 40 cells", () => {
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assert.deepEqual(
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startDrops(3, always(0)).map((row) => row === 0),
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[true, true, true],
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);
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assert.deepEqual(startDrops(2, always(0.5)), [-20, -20]);
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for (const row of startDrops(200, Math.random)) {
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assert.ok(row <= 0 && row >= -40, String(row));
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}
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});
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test("a step moves every column down one row", () => {
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assert.deepEqual(stepDrops([-3, 0, 5], 10_000, always(0)), [-2, 1, 6]);
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});
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test("a column past the bottom restarts only on a high enough roll", () => {
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const past = [Math.ceil(100 / CELL) + 1];
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assert.deepEqual(stepDrops(past, 100, always(0.99)), [1]);
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assert.deepEqual(stepDrops(past, 100, always(0.5)), [past[0] + 1]);
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});
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test("a column still on the canvas never restarts", () => {
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assert.deepEqual(stepDrops([2], 100, always(0.99)), [3]);
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});
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test("a step does not change the array it was given", () => {
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const drops = [1, 2];
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stepDrops(drops, 100, always(0.99));
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assert.deepEqual(drops, [1, 2]);
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});
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test("the glyph comes from the set, first and last at the ends of the roll", () => {
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assert.equal(glyphFor(always(0)), GLYPHS[0]);
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assert.equal(glyphFor(always(0.999999)), GLYPHS[GLYPHS.length - 1]);
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});
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test("the fade colour keeps the background's channels at a low alpha", () => {
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assert.equal(fadeColorOf("rgb(30, 30, 46)"), "rgba(30, 30, 46, 0.09)");
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assert.equal(fadeColorOf("rgb(239,241,245)"), "rgba(239, 241, 245, 0.09)");
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assert.equal(fadeColorOf("rgba(1, 2, 3, 0.5)"), "rgba(1, 2, 3, 0.09)");
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});
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test("a colour with no channels fades from the default background", () => {
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assert.equal(fadeColorOf("transparent"), "rgba(30, 30, 46, 0.09)");
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assert.equal(fadeColorOf(""), "rgba(30, 30, 46, 0.09)");
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});
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